channeldb: add now function

Needed for time control in unit tests.

channeldb/db.go

@@ -129,6 +129,7 @@ type DB struct {
 	*bbolt.DB
 	dbPath string
 	graph  *ChannelGraph
+	now    func() time.Time
 }
 
 // Open opens an existing channeldb. Any necessary schemas migrations due to
@@ -162,6 +163,7 @@ func Open(dbPath string, modifiers ...OptionModifier) (*DB, error) {
 	chanDB := &DB{
 		DB:     bdb,
 		dbPath: dbPath,
+		now:    time.Now,
 	}
 	chanDB.graph = newChannelGraph(
 		chanDB, opts.RejectCacheSize, opts.ChannelCacheSize,